[LEBV-418] Fix document type dropdown default value

🎯 Summary

- Before

- Now

🧪 How to test

Launch the Lebara-Video environment

Run in a terminal the branch 'develop' in the lebara-video-deployment project.
Execute docker-compose -f docker-compose-backend-mock.yml up.

Launch the onboarding-frontend

Run in a terminal the branch 'LEBV-418_fix-document-type-placeholder' in the lebara-onboarding-frontend project.
Run the project.
Open in one tab http://localhost:4200/?msisdn=015166804082&iccid=1847.
In the step 2 you should see something similar to the attached image.

🧠 Considerations

🧐 Checklist

Changes work in Google Chrome
Changes work in Safari
UI is responsive